How to exercise in the hot weather

My last blog discussed the importance of using a heart rate monitor (HRM) to optimize your exercise for weight loss. A HRM is also a valuable tool for exercising in the heat. After a rainy cool spring, the weather has turned unseasonably hot (especially in certain areas of the US). Without time to acclimate, many people go indoors or stop their exercise. It is true that exercising in the heat can be dangerous. However, if you allow your body to adapt to heat, you may be surprised. If you have achieved some fitness in the spring, that can help you maintain outdoor fitness during the heat of the summer. The following recommendations will help with your heat adaptation:

Allow two weeks for your body to develop the ability to exercise in heat.

Exercise with a heart rate monitor (HRM) during the heat adaptation phase.

Don’t be concerned that your pace is significantly slower.

Exercise early or late in the day when you can to avoid the intense sunlight and hottest temperatures.

Wear light breathable clothing.

Drink at least twenty ounces of fluid before you exercise.

Make sure that you maintain your electrolytes (salts).

Allow two weeks for you body to develop the ability to exercise in heat: The body has an incredible ability to adapt, given enough time. The body’s ability to dissipate heat requires several physical changes. If you wear a HRM you can see the work your body is doing to keep cool. My first run in the heat, my pace had slowed 45 seconds/mile slower at the same HR. Slowly over the next two weeks I regained my pace as my body adapted to the additional stress of the heat. You can see the stress of heat yourself. Go into a sauna or steam room and take your starting heart rate. Relax and watch your heart rate climb with no exercise. An increase of ten extra beats per minute is not unusual in less than 10 minutes.

During the heat adaptation phase, exercise with a heart rate monitor: Allow your body to work on heat adaptation by lowering your effort level. A great side effect is that body will want to shed body fat. In the winter, exposure to cold seems to increase the propensity to store fat. In the heat of the summer, the body seems to sense it can operate better without the winter fat stores.

Do not be concerned that your pace is significantly slower: Your pace will improve as your body adapts to heat. If you push too hard during the adaptation phase, you can soon become overwhelmed and show signs of overtraining.

Exercise early or late in the day when you can avoid the intense sunlight and hottest temperatures: Keep your exercise fun. Running at noon on a hot day generally is a bad idea. In many areas of the country the lows in mid summer are around 80F. Running or walking in the morning keeps you outside, but does not drain your energy for the rest of the day.

Wear light breathable clothing: The new synthetic, breathable materials are great for training in the heat. Occasionally I have seen overweight walkers with a sweat suit walking in heat. I guess the idea is that if you sweat more, the more weight you will lose. This line of thought is dangerous. Weight loss from water loss is gained back quickly. As little as five percent loss of weight through sweat can cause negative physiologic consequences. It is better to help your body dissipate heat by draping a wet towel on your neck. Sun visors are better than hats because they do not trap heat from the head.

Drink at least twenty ounces of fluid before you exercise: Pre-workout hydration gives your body a head start on maintaining fluid. Try to consume twenty ozs. of water or electrolyte replacement drink fifteen to thirty minutes before you exercise. This much fluid allows the water to “dump” into the gut faster, where it can be absorbed. Drinking smaller amounts of water just before your exercise tends to cause the liquid to slosh in your stomach. If you wait until you are thirsty to drink, you are already on your way to dehydration.

Make sure that you maintain your electrolytes (salts): Sodium, potassium, chloride and magnesium are the most important electrolytes. Sodium is by far the most common electrolyte that causes problems. Low sodium can interfere with a number of important physiologic functioning. There are a variety of electrolyte replacement drinks and gels on the market. If you are not out for too long a salty food (like a pretzel) and a banana will probably do the job.

Unless you have a special health risk, you probably can adapt to the stress of warm weather training. A heart rate monitor helps monitor your body’s stress level and can tell you when its time to quit. If you see a significant rise in your heart rate without a commensurate increase in effort level, your body has reached its limit. Be smart and train safely this summer.

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ABOUT THE AUTHOR

Larry Krutka

Larry has been a fitness consultant for 19 years. He has competed in triathlons at an international level for over two decades, competing in the Hawaii Ironman World Championships six times. He was an All...read more